Engine starter



Nov. 12, 1940. J. w. FlTz GERALD 2,221,083

v ENGINE STARTER Filed Aug. 18, 1939 2 sheets-sheet 1 \\\\\\\\\\\\\\\\\\\\\\\"glx L/27/7/7 MZFm/d Nov. 12, 1.940. J. W. FlTz GERALD 2,221,083

ENGINE STARTER Fil'ed Aug. 18, 1959 2 Sheets-Sheet 2 Patented Nov. 12, 1940 ENGINE STARTER John W. Fitz Gerald, Milwaukee, Wis., assignor to Briggs & Stratton Corporation, Milwaukee,

Wis., a corporation of Delaware Application August 18, 1939, Serial No. 290,741

This invention relates to engine starters, and refers particularly to the so-called automatic starters used in automobiles.

As is well known, in starters of this type,

a driving pinion is propelled longitudinally to and from an operative position meshing with the ring gear of the engine, through a driving mechanism generally incorporating a threaded connection between the pinion and its driving 0 element. It is, ofcourse, necessary to limit the endwi-se motion of the pinion toward its operative position when it is fully meshed with the ring gear, and in the past, this has been generally done by having the pinion strike a stop collar fixed to the drive shaft. This manner of arresting the forward motion of the pinion is objectionable in that it requires drilling of the shaft and is also quite noisy as there is a decided clank when the pinion engages the collar.

'I'his invention therefore has as one of its objects to improve engine starters of this type by obviating the necessity for a separate stop secured to the drive shaft, and by substituting a stop which yieldingly arrests the forward propulsion of the pinion to thereby eliminate the noise incidental thereto.

Another object of this invention` is to provide an engine starter of the character described wherein the driving force is applied from the shaft to the pinion through a resilient driving element which provides both torsional and endwise resiliency, and wherein the forward propulsion of the pinion is arrested through pressure exerted on this same resilient driving ele- 35 ment.

Another object of this invention is to provide an engine starter of the character described which is a complete unitary assembly independent of the drive shaft to facilitate installation 40 thereof.

A further object of this invention is to provide an engine starter of the character described in which the resilient driving element is totally enclosed to preclude the possibility of oil and 45 other foreign matter coming in contact with it and interfering with its proper driving function. With the above and other objects in view which will appear as the description proceeds,

this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come Within the scope of the claims.

'I'he accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereoffand in which: 5

Figurel is a side view partially in section, illustrating an engine starter constructed in accordance with this invention,.the parts being in their normal inactive positions;

Figure 2 is a view similar to Figure 1, but 10 showing the parts in their positions at the time the pinion strikes the ring gear;

Figure 3 is a view similar to Figure 1, illustrating the pinion partly meshed with the ring gear;4 and r Figure 4 is a view similar to Figure 1, showing the position of the parts at the time the pinion is fully meshed and forward propulsion ceases.

Referring now particularly to the accompanylng drawings in which like numerals indicate 20V like parts, the numeral 5 designates the drive shaft of a starting motor G, upon which a pinion 'I is slidably and freely rotatably mounted to be automatically moved to and from an operative position meshing withV a ring gear 8.

The pinion 'I carries an extension 9 which projects out toward the end of the drive shaft. This extension has a threaded portion I0 and an unthreaded portion II, the threaded Lportion being adjacent to the pinion. Threaded on the 30 pinion extension is a driving member I2, the outer end portion I3 of which is slidable on the unthreaded portion II of the extension.

Medially of its ends, the driving member has an annular flange I4. The outer face of this fiange provides a friction surface with which one end of an annular resilient driving element I5 engages. While this driving element may be formed of any suitable material, it is preferably a semi-stiff rubber having adequate cubical elaso ticity and a relatively high coefficient of surface friction.

If the driving element is formed of rubber, it is obviously not compressible though highly resilient. A compressible resilient material, such as a cork base composition, may be used with equal facility, and it is to be understood that where reference is made in this specification and the claims to a resilient driving member, one `formed of compressible resilient material is not to be excluded. y

Encircling the rubber collar and the flange I4 is a cup-like member I6 reduced in diameter at its outer end to fit the drive shaft and be secured thereto as by a set screw Il.

The outer extremity of the cup-like member is spun over to provide an abutment I8 engaging the ange I4 to limit movement of the driving member toward the pinion and thereby maintain 5 the rubber collar ina degree of initial deformation.

Interposed between the bottom of the cuplike member and the adjacent end of the rubber collar is a washer or collar I9 which is slidable on the unthreaded portion II of the pinion extension, for a purpose to be hereinafter described.

The dimensions of the rubber collar are such when the parts are in their normal positions, as shown in Figure '1, that the outer cylindrical surface of the collar is in frictional contact with the inner wall of the cup-like member, and the friction surface of the flange I4 on the driving member frictionally grips the adjacent end of the collar. Hence, it will be apparent that a iitational force is yieldingly applied from the shaft through the rubber collar to the driving member. f

As a consequence, upon initial rotation of the drive shaft to effect starting of the engine, the pinion 1, by virtue of the threaded connection between its extension and the driving member and its inertia, is propelled forwardly toward the ring gear. If the teeth of the pinion accidentally abut those of the ring gear, the rubber collar is deformed slightly by pressure between the driving member and the cup-like member until the frictional force of the improperly meshing teeth is overcome, whereupon the pinion turns slightly and forward propulsion continues.

As the pinion approaches its operative position fully meshed with the ring gear, a stop collar 20 threaded to theouter vend of the pinion extension and freely movable in an annular space 40 2I formed by a counterbore in the cup-like member, abuts the collar or washer I9, as shown in Figure 3. From this point, a balance exists between the forces tending to propel the pinion forwardly and tending to move the driving member 45 rearwardly by virtue of the threaded connection therebetween, andas a consequence, continued rotation of the driving member with respect to the pinion deforms the rubber collar by endwise pressure between the flange I4 and the collar or 50 washer I9, as shown in Figure 4.

This deformation continues until the space defined by the sleeve I3 on the driving member, the flange I4, the washer or collar I9, and the shell I6, has been reduced to the volume of the rubber 55 collar. When this occurs, the pinion is fully meshed, as clearly shown in Figure 4, and as endwise motion of the pinion is now fully arrested, it follows that the continued rotation of the drive shaft is transmitted to the pinion to pick up the 60 load of the engine through the torsional resiliency of the rubber driving element.

Upon starting of the engine, the overrunning action of the pinion effects its retraction to restore the parts to their initial positions, shown 65 in Figure 1.

Of course, it is to be understood that the rubber collar will be deformed to its extreme limit only when the load of the engine is excessive, as in cold weather when the grease is thick. In most 70 instances, only a partial deformation of the rubber collar will take place.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent that this invention entirely 75 obviates the need for a separate stop collar secured to the drive shaft, and that it cushions the endwise movement of the pinion toward its operative position through the resiliency of the rubber driving element, thereby not onlyproviding a more unitary construction, but insuring quieter operation.

What I claim as my invention is:

1. In an engine starter including, a power shaft, and a pinion movable longitudinallywith respect to the shaft to andI from ann operative position: means for drivingthe pinion from the Shaft comprising, a body of cubically elastic material having a high coenicient of friction; a member fixed with respect to the shaft and frictionally engaging a surface of said elastic body; a driving member having a portion thereof frictionally engaging another surace of said elastic body; a sleeve on the pinion; a threaded connection between the driving member and the pinion sleeve whereby relative rotation between the driving member and pinion effects endwise motion of one with respect. to the other; and means acting through said elastic body for yieldingly limiting endwise movement of the pinion toward operative position.

2. In an engine starter having a drive shaft, and a pinion movable longitudinally with respect to the drive shaft to and from an operative position: means driven from the shaft for effecting such motion of the pinion and for transmitting rotation to the pinion including, a body of cubically elastic material' through which rotation of the shaft is transmitted into longitudinal and rotary movement of the pinion; and means for limiting longitudinal motion of the. pinion toward operative position through deformation of said resilient body.

3. In an engine starter having a drive shaft and a pinion movable longitudinally with respect to the shaft and rotatable therewith: a threaded extension on the pinion; a driving member threaded on said extension and having a friction surface; an annular elastic body engaging said surface with a frictional contact; -a member fixed toA the drive shaft and having a portion thereof frictionally engaging said annular elastic body; and means carried by the threaded pinion extension and operable to compress the elastic body between it and the friction surface of the driving member to limit longitudinal movement of the pinion toward its operative position.

4. In an engine starter having a drive shaft and a pinion movable longitudinally with respect thereto and rotatably therewith: an extension on the pinion having a threaded portion and an unthreaded portion; a driving member threaded on said extension and having a friction surface adjacent to the unthreaded portion of the extension; a resilient annular body frictionally engaging said frictionv surface; a member fixed to the drive shaft and having a portion thereof frictionally engaging said resilient body to res'iliently transmit rotation from the shaft to the driving member; a collar slidable on the unthreaded portion of the pinion extension and engaging a surface of the resilient body opposite the friction surface of the driving member; and a stop on the unthreaded portion of the pinion extension engageable With-'said collar upon relative endwise motion between the pinion and driving member in a direction to 5. In an engine starter having a drive shaft and a pinion movable logitudinally with respect thereto to and from an operative position: an extension on the pinion having a threaded portion; a stop collar on the outer end of said ex.- tension; a driving member threadedon the extension and having a friction surface spaced from the stop collar and opposed thereto; a collar loose on the extension and engageable with ;0 the stop collar; a resilient body interposed between said collar and the friction surface of the driving member; and a member fixed to the drive shaft and having a cup-like portion engaging over the resilient body and frictionally J engaging a surface thereof.

6. In an engine starter having a drive shaft and a pinion movable longitudinally with respect thereto: a member fixed to the drive shaft and having a cup-shaped inner end portion pro- 20 viding an annular space encircling the drive shaft; an extension on the pinion projected into said annular space, said extension having a vthreaded portion; aI driving member having a threaded connection with said portion and having a part disposed inside said annular space; a frictional driving element-for transmitting rotation from said first named member to the driving member; and means wholly disposed inside said annular space for limiting longitudinal movement of the pinion toward operative position.

7. In an engine starter having a drive shaft and a pinion movable longitudinally with respect thereto to and from an operative position:

a cup-like member fixed to the outer end of the drive shaft and providing an annular space encircling the shaft; 'a threaded extension on the pinion extending into the annular space; a driving member having a threaded connection with l0 said extension whereby relative rotation between the extension and the driving member effects longitudinal motion of the pinion; a resilient driving element lraving frictional engagement with the driving member and said cup-like mem- 15 ber whereby rotation is yieldingly transmitted from the cup-like member to the driving member; and means operable to deform said driving element and limit longitudinal motion of the pinion toward operative position, said means be- 50 ing wholly disposed within said annular space.

8. In an engine starter having a drive shaft and a pinion movable longitudinally with respect thereto to and from an operative position: a cup-like member fixed to the outer end of the drive shaft and providing an annular space encircling the shaft; a threaded extension on the pinion extending into the annular space; a driving member having a threaded connection with said extension whereby relative rotation between the extension and the'driving member effects longitudinal motion of the pinion; a resilient driving element having frictional engagement with the driving member and said cup-like member whereby rotation is yieldingly transmitted from the cup-like member to the driving member; means operable to apply endwise pressure on said driving element and limit longitudinal motion of the pinion toward operative position, said means being wholly disposed within said annular space; and means for limiting the deformation of the driving element effected by the endwise pressure thereon. l I9. In anengine starter having a drive shaf and a pinion movable longitudinally with respect thereto to and from an operative position: an extension on the pinion having a threaded portion and an unthreaded portion; a driving member threaded on the extension and having an annular flange providing a friction surface substantially normal to the axis of the shaft and disposed adjacent to the unthreaded portion of the pinion extension; a cup-shaped member fixedto the shaft and extending over said annular flange of the driving member to cooperate therewith in forming a substantially closed annular space surrounding the pinion extension; an annular body of resilient material having a high coefficient of friction confined in said space with one wall thereof in frictional engagement with the flange and another wall thereof in frictional engagement with' the cup-shaped member; a collar slidable on the unthreaded portion of the pinion extension and engaging the surface of the annular body opposite the annular fiange; and a stop collar on the unthreaded portion of the pinion extension engageable with the collar upon relative endwise motion between said pinion and the driving member in a direction to propel the pinion to its operative position whereby motion of the pinion to its operative position is yieldingly arrested.

JOI-IN W. FITZ GERALD. 

